In certain turbochargers or other turbine-based systems, exhaust flow may be received in the intake of the turbine in a direction co-axial with the shaft of the turbine. To enable delivery of the flow to the turbine blades at a desired angle of incidence, the axial flow is redirected by nozzle vanes in the turbine inlet to a desired flow direction that is angled with respect to the turbine shaft.
In some examples, turbocharger systems may include two turbochargers configured in series, such as a high pressure turbocharger fluidically coupled to a low pressure turbocharger. The exhaust of the turbine of the high pressure turbocharger may be delivered to the intake of the turbine of the low pressure turbocharger. To enable an axial flow into the intake of the low pressure turbine, in one example the high and low pressure turbines may be positioned facing one another with their shafts collinear. Such a configuration may create complicated fluidic coupling requirements between the respective high and low pressure compressors associated with the high and low pressure turbines, as extensive turning and routing of the flow between the compressors may be required. Such fluidic coupling requirements may also increase the packaging space required for the turbocharger system within the associated engine.
In other examples, the high and low pressure turbines may be positioned with their shafts offset from parallel and forming an angle. In such examples, to enable axial flow into the intake of the low pressure turbine, the exhaust flow from the high pressure turbine must be turned through bends of between 0 to 180 degrees. Turning the exhaust flow in this manner may create secondary flows that can lead to undesirable boundary layer separation, pressure losses, and/or non-uniform flow into the low pressure turbine intake. In these configurations, complicated centerbodies may also be necessary to manage the flow into the low pressure turbine intake.